1. Field of the Invention
The present invention relates to an ion implantation apparatus used for surface modification of materials.
2. Description of the Prior Art
Ion implantation apparatuses have been mainly used for doping processes to semiconductors. In recent years, there has been a strong demand of applying the ion implantation technique to surface modification of materials. To meet the demand, various researches and developments have been made.
The ion implantation apparatuses conventionally used for the surface modification are of a type in which only parts of the end stations of the apparatuses used in the field of the semiconductors are improved. They are very low in the processing ability, processing time, productivity and the like, that is, being only in a level of the so-called laboratory apparatus.
Recently, there has been proposed an ion implantation apparatus for the surface modification, having a high performance and being suitable for the industrial applications, in Japanese Patent Laid-open No. hei 1-97363 (U.S. Pat. No. 4,994,164). This apparatus comprises a plurality of cathodes and an electrode structure corresponding to the surface geometry of the target. Similarly, Japanese Patent Laid-open No. hei 2-239543 discloses an ion implantation apparatus including arc ion sources having a plurality of cathodes.
With use of the ion implantation apparatus of a type described above, it is possible to easily perform the surface modification for a target having a large surface. However, the complicated electrode structure thereof brings inconveniences of making it difficult to obtain uniform ion beams and of complicating the structure of the apparatus itself. Further, since an acceleration electrode provided on each arc ion source is applied with a voltage of several tens kV, it is not easy to form the electrode structure in correspondence to the surface geometry of a target in terms of the insulation.